A method for identifying a bad GSM speed frame and simultaneously maintaining a frame erasure rate below a specified value. The method is based upon a joint use of four signal quality metrics: (1) frame CRC parity check; (2) estimated burst signal-to-noise ratio; (3) estimated frame bit error count; and (4) stealing flag values of a frame. Another feature includes providing an improved estimated burst signal-to-noise ratio.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A Radio Frequency (RF) receiver comprising: a demodulator that is operable to receive a plurality of bursts that make up a speech frame and to convert the plurality of bursts to a baseband signal, wherein each of the plurality of bursts includes coded speech data and a received training sequence; at least one digital processing component communicatively coupled to the demodulator to receive the baseband signal and that is operable to process the baseband signal for each of the plurality of bursts to: perform a plurality of correlation operations on a respective received training sequence using a local sequence to produce a plurality of correlation sequences, each correlation sequence including a plurality of correlation values and being respective to a contiguous portion of the training sequence; separately sum the correlation values of the correlation sequences to produce a plurality of sums; based upon one of the plurality of sums, determine an estimated signal power; determine an estimated noise power based upon the received training sequence; based upon the estimated signal power and the estimated noise power, determine an estimated signal-to-noise ratio (ESNR) for the respective burst; compare the ESNR of each of the plurality of bursts to an ESNR criteria; and consider comparisons of the LSNRs of the plurality of bursts to the ESNR criteria in determining whether to indicate that the speech frame is bad.
2. The RF receiver of claim 1 , wherein in separately summing the correlation values of each correlation sequence to produce a plurality of sums, the at least one digital processing component is operable to separately sum absolute values of the correlation values of the correlation sequences.
3. The RF receiver of claim 1 , wherein: each training sequence includes 26 symbols; each correlation sequence includes 16 symbols; and each of the plurality of correlation sequences includes 11 correlation values.
4. The RF receiver of claim 1 , wherein the at least one digital processing component is operable to determine an estimated noise power based upon the received training sequence by: selecting a correlation sequence of the plurality of correlation sequences having a maximum summation as an estimated channel impulse response; convolving the estimated channel impulse response with a local training sequence to produce an estimated transmitted training sequence; and performing a power summation of the difference between the estimated transmitted training sequence and the respective received training sequence to produce the estimated noise power.
5. The RF receiver of claim 1 , wherein the at least one digital processing component is operable to determine that the speech frame is bad when any M ESNRs of the plurality of bursts are less than a predetermined SNR threshold, wherein M is a positive integer.
6. The RF receiver of claim 1 , wherein the at least one digital processing component is operable to determine that the speech frame is bad when: any M ESNRs of the first N bursts corresponding to the speech frame are less than a predetermined SNR threshold, where N is a positive integer, M is a positive integer, and M is less than N; and any M LSNRs of the last N bursts corresponding to the speech frame are less than a predetermined SNR threshold.
7. The RF receiver of claim 1 , wherein the at least one digital processing component is further operable to: perform a Cyclical Redundancy Check (CRC) on the speech frame; and consider the CRC of the speech frame in determining whether to indicate that the speech frame is bad.
8. The RF receiver of claim 1 , wherein the at least one digital processing component is further operable to: perform a Cyclical Redundancy Check (CRC) on the speech frame; consider the CRC of the speech frame in determining whether to indicate that the speech frame is bad; determine an Estimated Bit Error Count (EBEC) for the speech frame; and consider the EBEC of the speech frame in determining whether to indicate that the speech frame is bad.
9. The RF receiver of claim 1 , wherein the at least one digital processing component is further operable to: extract at least one stealing flag from the speech frame; and consider at least one value of the at least one stealing flag in determining whether to indicate that the speech frame is bad.
10. The RF receiver of claim 1 , wherein the at least one digital processing component is further operable to: extract at least one stealing flag from the speech frame; consider at least one value of the at least one stealing flag in determining whether to indicate that the speech frame is bad; perform a Cyclical Redundancy Check (CRC) on the speech frame; and consider the CRC of the speech frame in determining whether to indicate that the speech frame is bad.
11. The RF receiver of claim 1 , wherein the at least one digital processing component is further operable to: extract at least one stealing flag from the speech frame; consider at least one value of the at least one stealing flag in determining whether to indicate that the speech frame is bad; determine an Estimated Bit Error Count (EBEC) for the speech frame; and consider the EBEC of the speech frame in determining whether to indicate that the speech frame is bad.
12. The RF receiver of claim 1 , wherein the at least one digital processing component is further operable to: extract at least one stealing flag from the speech frame; consider at least one value of the at least one stealing flag in determining whether to indicate that the speech frame is bad; determine an Estimated Bit Error Count (EBEC) for the speech frame; consider the EBEC of the speech frame in determining whether to indicate that the speech frame is bad; perform a Cyclical Redundancy Check (CRC) on the speech frame; and consider the CRC of the speech frame in determining whether to indicate that the speech frame is bad.
13. The RF receiver of claim 1 , wherein the at least one digital processing component is further operable to: decode the coded speech data of the plurality of bursts to produce decoded speech data; encode the decoded speech data to produce re-encoded speech data; compare the re-encoded speech data to the coded speech data to determine an Estimated Bit Error Count (EBEC) for the speech frame; and consider the EBEC of the speech frame in determining whether to indicate that the speech frame is bad.
14. A Radio Frequency (RF) receiver comprising: a demodulator that is operable to receive a plurality of bursts that make up a speech frame and to convert the bursts to a baseband signal, wherein each of the plurality of bursts includes coded speech data, a received training sequence, and at least one stealing flag; and at least one digital processing component communicatively coupled to the demodulator to receive the baseband signal and that is operable to process the baseband signal for each of the plurality of bursts to: extract the at least one stealing flag from the speech frame; consider values of the at least one stealing flag in determining whether to indicate that the speech frame is bad; determine an absolute value of the sum of the stealing flags contained in the plurality of bursts; and consider the absolute value of the sum of the stealing flags in determining whether to indicate that the speech frame is bad.
15. The RF receiver of claim 14 , wherein the at least one digital processing component is further operable to: determine an Estimated Bit Error Count (EBEC) for the speech frame; and consider the EBEC of the speech frame in determining whether to indicate that the speech frame is bad.
16. The RF receiver of claim 15 , wherein in determining an Estimated Bit Error Count (EBEC) for the speech frame, the at least one digital processing component is operable to: decode the coded speech data of the plurality of bursts to produce decoded speech data; encode the decoded speech data to produce re-encoded speech data; compare the re-encoded speech data to the coded speech data; and determine the EBEC based upon a number of disagreements between the re-encoded speech data and the coded speech data is the EBEC.
17. The RF receiver of claim 14 , wherein the at least one digital processing component is further operable to: perform a Cyclical Redundancy Check (CRC) on the speech frame; and consider the CRC of the speech frame in determining whether to indicate that the speech frame is bad.
18. A Radio Frequency (RF) receiver comprising: a demodulator that is operable to receive a plurality of bursts that make up a speech frame and to convert the bursts to a baseband signal, wherein each of the plurality of bursts includes coded speech data and a received training sequence; and at least one digital processing component communicatively coupled to the demodulator to receive the baseband signal and that is operable to process the baseband signal for each of the plurality of bursts to: decode the coded speech data of the plurality of bursts to produce decoded speech data; encode the decoded speech data to produce re-encoded speech data; compare the re-encoded speech data to the coded speech data; determine an Estimated Bit Error Count (EBEC) based upon a number of disagreements between the re-encoded speech data and the coded speech data; and consider the EBEC of the speech frame in determining whether to indicate that the speech frame is bad.
19. The RF receiver of claim 18 , wherein the at least one digital processing component is further operable to: perform a Cyclical Redundancy Check (CRC) on the speech frame; and consider the CRC of the speech frame in determining whether to indicate that the speech frame is bad.
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July 2, 2004
January 23, 2007
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